According to a prior solution of the assignee of the present application (Italian application no. 9494 A/85 and German application No. P 36 31 940.6), there are provided downstream of said cutting bars: a crosspiece, on which the successive manufactured articles are laid down, two pressure elements acting alternately in order to retain the manufactured articles on the crosspiece, the first of which pressure elements is raised in order to make pass the new manufactured article to be accumulated, while the other pressure element acts on the rear end portion of the manufactured articles of the stack in a sheltered condition below the trajectory of the manufactured article to be accumulated; said first pressure element is lowered in order to act on the stack during a stage of interruption of the advance of a new manufactured article, while said other pressure element is raised in order to receive the rear end portion of the last manufactured article which has just been accumulated and retained by the first pressure element; blowing means are provided in order to favor the positioning and the cooling of the weld of the end of the manufactured article which has just been formed.